SPOTTED OWL SURVEYS IN THE CEDAR RIVER WATERSHED 2008 Surveys Seattle Public Utilities Cedar River Watershed King County, Washington October 30, 2008 RAEDEKE ASSOCIATES, INC. Report To: Seattle Public Utilities Cedar River Watershed 19901 Cedar Falls Road S.E. North Bend, WA 98045 Title: Spotted Owl Surveys in the Cedar River Watershed – 2008 Survey Report Project Number: 2008-013-001 Prepared by: Dale R. Herter RAEDEKE ASSOCIATES, INC. 5711 N.E. 63rd Street Seattle, Washington 98115 (206) 525-8122 Date: October 30, 2008 Project Manager: Dale R. Herter, M.S. Wildlife Biologist Current Project Personnel: Joel W. Merriman, M.S. Wildlife Biologist Kurt Richardson, B.S. Wildlife Technician Connie Holloway Wildlife Technician TABLE OF CONTENTS Page LIST OF TABLES.............................................................................................................. v LIST OF FIGURES ............................................................................................................ v 1.0 INTRODUCTION ....................................................................................................... 1 2.0 METHODS .................................................................................................................. 2 3.0 RESULTS ....................................................................................................................4 3.1 Weather....................................................................................................................4 3.2 Responses................................................................................................................. 4 4.0 DISCUSSION.............................................................................................................. 6 4.1 Survey Results ......................................................................................................... 6 4.2 Recommendations for Future Studies...................................................................... 6 5.0 LITERATURE CITED ................................................................................................ 7 APPENDIX..................................................................................................................... A-1 iii LIST OF TABLES Table Page 1. Survey Dates for Spotted Owl Surveys ................................................................... 12 2. Summary of Owl Responses.................................................................................... 13 LIST OF FIGURES Figure Page 1. Map of the Cedar River Watershed Showing Old Forest Patches........................... 13 2. Findley Lake Survey Area Map............................................................................... 14 3. Goat Mountain Survey Area Map............................................................................ 15 4. McClellan Survey Area Map ................................................................................... 16 5. Meadow Mountain Survey Area Map...................................................................... 17 6. Rex River Survey Area Map.................................................................................... 18 7. Tinkham/Abiel/Baldy Survey Area Map................................................................. 19 8. 2008 Owl Responses................................................................................................ 20 iv 1 1.0 INTRODUCTION The Cedar River Watershed is one of the primary sources of water for the City of Seattle and encompasses a large reservoir – Chester Morse Lake. Much of the forest in the watershed has been previously harvested and now occurs in multi-age stands of second- growth timber. The Watershed consists of over 90,000 acres of predominantly forested, mountainous lands extending from the Cascade Crest, just south of Snoqualmie Pass in central Washington, westward to just south of North Bend, Washington. Approximately 14,000 acres or 6.5% of the forest land in the Watershed has not been harvested, and exists as natural stands of mature and old-growth forest. The majority of old-growth forest in the Cedar River Watershed occurs in 6 distinct patches. These are primarily located in the upper reaches of the watershed (Figure 1). There are historic northern spotted owl (Strix occidentalis caurina) responses within these 6 patches of old forest; however, none of the established sites have had documented detections of a spotted owl since 1997. Surveys at one spotted owl site were performed annually from 1997 through 2000 (D.R. Herter, S. Nickelson, pers. obs.). Blanket surveys for spotted owls were conducted at the 6 old forest patches in 2005 (Raedeke Associates, Inc. 2005). No spotted owls were detected during these surveys. In the summer of 2008, Raedeke Associates, Inc. staff conducted a series of calling surveys for northern spotted owls in the same 6 patches of old forest within the Cedar River Watershed. This survey program was initiated as part of the requirements set forth under the Cedar River Watershed Habitat Conservation Plan (HCP; City of Seattle 2000), established in 2000. This agreement between the City of Seattle, the U.S. Fish and Wildlife Service, and the National Marine Fisheries Service was developed to protect habitat within the watershed for selected birds, mammals, and fish. According to the Plan, a thorough survey for spotted owls at old forest patches within the watershed would occur within 3-10 years following its acceptance. The 2005 spotted owl study constituted the initial survey of the watershed for the purpose of determining the presence or absence of spotted owls following the establishment of the HCP. The 2008 study represents the second year of surveys within this 10 year period following the establishment of the HCP. Spotted Owl Surveys – 2008 Raedeke Associates, Inc. Cedar River Watershed October 30, 2008 2 2.0 METHODS The 2008 spotted owl survey procedures followed recommended U.S. Fish and Wildlife Service guidelines (USFWS 1992). The 6 survey areas and stations surveyed were originally selected by Watershed biologists in 2005, and were replicated in 2008. We did not survey the smallest block of old forest habitat (McClellan Butte) during our first visit, but initiated surveys at this block for all subsequent visits. Spotted owls prefer territories with a large block of old forest surrounding a selected nest tree or trees (Ripple et al. 1991, Swindle et al. 1999, Dugger et al. 2005). All of the 6 survey areas in the Watershed contained historic spotted owl responses and/or known spotted owl territories. The theory behind the surveys is that if spotted owls were not detected in these patches, which represent the best available habitat, then they were unlikely to occur in other areas which were typified by second-growth conifer or mixed forest with few, if any, remaining old-growth patches or remnant old-growth trees. The surveys were conducted at a series of pre-selected calling stations placed in and on the edge of spotted owl habitat stands, with the intent to attain complete coverage of suitable habitat (in this case, old forest patches; Figures 2 – 7). Road stations were surveyed during hours of darkness and hiking stations were surveyed during the day (typically in late afternoon, immediately prior to night surveys). Night surveys were initiated after civil twilight, generally when the forest became dark enough to ensure that potential diurnal spotted owl predators [primarily goshawks (Accipiter gentilis)and red- tailed hawks (Buteo jamaicensis)] were no longer active. Surveys were completed within the recommended survey season of March 15th to August 31st (though this has been extended to September 15th in Washington), which corresponds to the typical breeding season for the species. Four surveys were completed at the McClellan Butte site, and 5 surveys were conducted at each of the remaining survey areas (Table 1). To the extent possible, survey visits were spaced throughout the season in order to detect any potential nesting birds early in the season, and later to detect owls that may have emigrated to the Watershed during the later portion of the breeding period. However, due to unusually heavy snow pack in the Watershed in spring 2008, survey initiation was delayed until July due to snow blockage on the road system. Surveys were halted and rescheduled if rain was moderate or heavy, or if tree-drip or winds greater than 10 mph interfered with surveyor hearing. We did not initiate a night of surveys if weather conditions appeared to be severe enough to preclude an evening of survey work. During a typical survey, personnel remained outside of their vehicles at each station for at least 10 minutes, alternately broadcasting spotted owl calls and listening for responses . Surveyors used their voices, “hoot-flutes,” and recordings of spotted owl calls to elicit responses. All owls heard during each 10-minute survey were noted. If a great horned Spotted Owl Surveys – 2008 Raedeke Associates, Inc. Cedar River Watershed October 30, 2008 3 owl (Bubo virginianus; another potential predator) responded, the surveyor listened for the remainder of the 10-minute period but did not broadcast any additional spotted owl calls. If a barred owl (Strix varia) responded, surveyors listened until the owl stopped calling, then gave additional spotted owl calls following a 2-5 minute period of silence. Barred owls are not known to prey on spotted owls, but may attack spotted owls. A typical evening survey, conducted under appropriate